1. Ch. 10
Forces

2. Forces

3. What is a force
When you ride a bike, your foot pushes against the pedal. The push makes the wheels of the bike move.
When you drop something, it is pulled to the ground by gravity.

4. What is a force Is a push or a pull.
a force is described by a push or a pull in particular direction.
Forces are measured in Newton.
Named after Isaac Newton.
You exert one Newton of force when lifting a lemon.
What SI unit measure forces?

5. Forces Can make objects move Can make objects move faster
Can make objects move slower
Can make objects stop moving
Can make objects change direction
Can make objects change shape

6. Combining forces
Often, more than a single force acts on an object at one time.
A combination of forces on an object is called the net force.
When forces that act in the same direction, the net force can be found by adding the strengths of the individual forces.
When forces act in opposite directions, they also combine to produce a net force. (subtract)

7. Combining Forces

8. Unbalanced Forces
Whenever there is a net force acting on an object, the forces are unbalanced.
These forces can cause an object to start moving, stop moving, or change direction.
Top is balanced
Bottom is unbalanced

9. Balanced Forces
Equal forces are acting on one object in opposite directions are called balanced forces.

10. Answer the following Questions
Find the Net Force?
5 N
3 N
10 N
10 N
5 N
32 N
5 N
10N 5N

11. Section 2 Friction and Gravity
Friction is the force that two surfaces exert on each other when they rub together.
The strength of the force of friction depends on two factors.
How hard they push together and they type of surfaces involved.
A smooth surface is much easier to slide on.

12. Friction

13. Gravity A force that pulls two objects towards each other.
Two factors that affect gravity
Mass- the more mass the greater the gravitational pull.
Distance- the farther apart two objects are the less gravitational pull.

14. Gravity

15. Section 3

16. Newton’s 1st law of motion or law of inertia
An object at rest will remain at rest, and an object at a constant velocity will stay at a constant velocity unless acted on by an unbalanced force.
Inertia is the tendency of an object to resist motion.

17. Newton’s 2nd law
Acceleration depends on the object’s mass on the net force acting on the object.
Acceleration=net force/ mass
Net force = mass X acceleration

18. Calculate
A speedboat pulls a 55 kg water skier. The force causes the skier to accelerate at 2.0 meters per second per second. Calculate the net force that causes this acceleration.